#coding:utf-8

import math

datas = [float(x) for x in input().split()]
p1 = (datas[0], datas[1])
p2 = (datas[2], datas[3])

print(math.sqrt(math.pow(p1[0]-p2[0], 2)+math.pow(p1[1]-p2[1],2))) import math math float(x) for x in input().split() for x in input().split() x input().split() ().split () input split for x in input().split() float(x) float x datas = [float(x) for x in input().split()] datas [float(x) for x in input().split()] p1 = (datas[0], datas[1]) p1 (datas[0], datas[1]) datas[0] datas 0 datas[1] datas 1 p2 = (datas[2], datas[3]) p2 (datas[2], datas[3]) datas[2] datas 2 datas[3] datas 3 print(math.sqrt(math.pow(p1[0]-p2[0], 2)+math.pow(p1[1]-p2[1],2))) print math.sqrt(math.pow(p1[0]-p2[0], 2)+math.pow(p1[1]-p2[1],2)) math.sqrt math sqrt math.pow(p1[0]-p2[0], 2)+math.pow(p1[1]-p2[1],2) math.pow(p1[0]-p2[0], 2) math.pow math pow p1[0]-p2[0] p1[0] p1 0 p2[0] p2 0 2 math.pow(p1[1]-p2[1],2) math.pow math pow p1[1]-p2[1] p1[1] p1 1 p2[1] p2 1 2 datas = [float(x) for x in input().split()] [float(x) for x in input().split()] datas p2 = (datas[2], datas[3]) (datas[2], datas[3]) p2 p1 = (datas[0], datas[1]) (datas[0], datas[1]) p1
#coding:utf-8

import math

datas = [float(x) for x in input().split()]
p1 = (datas[0], datas[1])
p2 = (datas[2], datas[3])

print(math.sqrt(math.pow(p1[0]-p2[0], 2)+math.pow(p1[1]-p2[1],2)))